Coating control device



arch 1967 H. J. MODERMOTT 3,308,787

COATING CONTROL DEVICE Filed July 22, 1965 United States Patent 3,363,787 COATHNG CONTROL DEVIQE Henry J. McDermott, Collingdale, Pa., assignor, by mesne assignments, to FMC Corporation, San Jose, Calif a corporation of Delaware Filed July 22., 1963, 592'. No. 296,847 3 Claims. (Cl. 118-125) This invention relates to a device for controlling the thickness of a coating on an elongated article such as a tape, strap or ribbon and more particularly to a device for providing a uniform thickness of coating by controlled removal of excess freshly or newly applied coating material.

One of the commercial methods of obtaining a uniform thickness coating on elongated articles such as straps and the like is by applying an excessive amount of coating material and then scraping or wiping oif the excess so that the residue of coating material is the desired thickness. This method is particularly applicable when the coating material is of the type which is in semi-liquid form when applied and subsequently sets or firms, either with or without some additional treatment. For example the coating may be a wax or resin which is applied while hot and in a viscous condition and which becomes firm at normal temperatures. Obviously the removal of the excess coating is carried out while the coating is fresh and before it has firmed or set, e.g. while the coating is still hot. The removal of the excess coating is generally accomplished by drawing the coated article over doctor blades or wipers or through a fixed die opening. Drawing through a fixed die opening generally results in a more uniform coating but for some types of products this procedure is not practicable. For example, a currently popular form of strap used for banding boxes, bales and the like consists of a plurality of high tenacity tire cord type strands adhesively secured together side-by-side. While an indefinitely elongated strap of this nature is substantially uniform in thickness and width over almost its entire length there are occasional knots tied in the individual strands and if the strap is excessively coated and then drawn through a fixed die opening to strip oif the excess coating, the knots will interfere with the passage of the strap through the opening. The present invention is directed toward providing a device especially useful for stripping excess coating from straps or the like of the type having occasional irregularities such as knots but which is also admirably adopted for use with straps or the like having complete dimensional uniformity.

It is an object of this invention to provide a device for removing excess coating material from a freshly coated strap-like article so as to leave a coating of uniform thickness on the article.

It is a further object of the invention to provide a device of' the above character which is readily adjustable so as to permit its use with straps of diiferent thicknesses or to permit the thickness of the coating material to be varied.

A further object of the invention is to provide a device for removing excess coating material from strap-like articles drawn therethrough and which is so constructed as to permit occasional excessively thick portions of the article to pass therethrough.

Still a further object of the invention is to provide a device for removing excess coating material from a straplike article drawn therethrough and which has provision for facilitating the lacing of the article therethrough.

Other objects, features and advantages of the invention will appear as the description of a preferred embodiment thereof proceeds.

Referring now to the drawing:

FIG. 1 is a side elevational view, partially in section and partially broken away, showing the device in use;

FIG. 2 is an end elevational view of the device;

FIG. 3 is a section taken on the line TIL-III of FIG. 2; and

FIG. 4 is a perspective view of a portion of a strap of the type in connection with the coating of which the full advantages of the invention are realized.

The type of strap in connection with the coating of which the invention finds its greatest utility is shown in FIG. 4 at 10. Said strap comprises a multiplicity of cords 11 adhesively secured together side-by-side in the form of a weftless fabric. Throughout almost all of its length the strap is of substantially uniform thickness and width but since the individual cords forming the strap are not infinite in length, there are occasional knots 12 tying the end of one cord to another. It is the presence of knots which creates particular problems when an attempt is made to coat the strap with a uniformly thick coating, particularly when the coating method comprises generally the application of an excessive amount of coating material followed by the subsequent wiping or scraping off of the excess coating so as to leave a coating of desired thickness. As will be seen, the device of the present invention solves these coating difficulties.

The device itself comprises a pair of substantially rectangular side plates 13 and 14 spaced apart a distance slightly greater than the width of the strap to be coated. Sandwiched between the side plates is a wiper member 15, secured to which by means of a screw 16 is a wiper head 17. Wiper member is held in fixed position between the side plates by means of screws, bolts or the like which pass through the side plates and the wiper member. A second wiper member 18 carrying a wiper head 19 is articulated between the side plates in a manner to permit wiper head 19 to be moved toward and away from Wiper head 17. For clarity of illustration, wiper member 18 is shown in FIG. 2 as being somewhat narrower than the spacing between side plates .13 and 14 but in the device itself said wiper member fits slidably between the side plates, there being just sufiicient looseness between the wiper member and the side plates to permit the wiper member to move. The lower edges of side plates 13 and 14 are spaced apart by spacer sleeves 20 and 21 through which extend screws or bolts 22 and 23 which hold the side plates in contact with the ends of the spacer sleeves. Wiper member 13 is provided with a cutout 24 which fits over spacer sleeve 21 and with an enlarged opening 25 through which spacer sleeve 2%) extends. Thus limited movement of wiper member 18 is permitted.

A lever 26 is pivotally mounted on a pin 27 press fitted into side plate 14. One corner of side plate 14 is cut away as indicated at 23 in FIG. 1 and a pin 29 ex tending through the cut away portion of the side plate pivotally connects one end of lever 26 to wiper member 18. Thus lever 26 may be employed to move wiper head 19 toward and away from wiper head 17, wiper member 18 both pivoting and sliding about spacer sleeve 21. Side plates 13 and 14 and the heads 17 and 19 of the wiper members provide a substantially rectangular slot 30 therebetween, the size of the slot being controllable by operation of lever 26.

A spring 31 extends through an opening 32 of lever 26 and a hook on the end of the spring extends about a pin 33 extending across the top or" the opening to anchor one end of the spring to the lever. At the other end spring 31 is anchored to a bracket 34 secured by screws or the like to side plate 14. Spring 31 urges lever 26 counterclockwise as viewed in FIG. 1, thus tending to move wiper head 19 into engagement with the fixed wiper head 17. An adjustment screw 35 is threaded through lever 26 and bears at one end against bracket 34. Screw 35 is provided with a manually operable head 36, said head Jeing rotatablyadjustable about the screw and locked to the screw in the desired rotated relationship by means of a set screw 37. Head 36 is provided with calibrations 38 shown in FIG. 2 and an indicating mark 39 is provided on side plate 14 in the vicinity of head 36. The abutment of the end of the adjustment screw 35 against bracket 34 of course limits the counterclockwise move ment of lever 26 and thereby in conjunction with spring 31 determines the spacing between wiper heads 17 and 19. Calibrations 38 may be of any suitable character such that when a particular one of the calibrations is aligned with the indicating mark 39 the size of slot 39 may be known and then by turning head 36 and the screw 35 to which said head is secured so as to align a diiierent calibration mark with mark 39 the size of slot 30 will be varied by a known amount. Since head 36 may be rotated relative to screw 35 by loosening the set screw 37, any desired calibration 38 may be aligned with the mark 39 as a starting reference position. If desired, a lock nut 40 may be provided for holding screw 35 in adjusted position.

A pair of pins 41 and 42 extend through side plates 13 and 14 and fixed wiper member 15 for mounting the device within a pair of brackets fixed to opposed walls of a tank containing the strap coating material. In FIG. 1 the coating tank is indicated at 4-3 and said tank has a pair of parallel side walls one of which is indicated at 44. Bracket 45 is secured to side wall 4-4 and said bracket is provided with a pair of upwardly directed open ended slots 46 and 47. There is a bracket similar to bracket 45 secured to the unshown side wall of the tank and the device of the present invention is suspended between the two brackets by the pins 41 and 4-2. In FIG. 1 pins 41 and 42 are shown located respectively within slots 46 and 47 of bracket 45 and it will be understood that the other ends of the pins are similarly associated with the unshown bracket.

As previously indicated, the device of the present invention is particularly adapted for removing excess coating material when the coating material is of a viscous nature, as for example a melted Wax or resin, such a coating commonly being referred to as a hot melt. The hot melt coating composition indicated at 50 is contained in tank 43 and from the drawing it will be seen that the lower portions of side plates 13 and 14 extend down into the melted coating material whereby the lower portion of the device is kept at an elevated temperature. Imbedded within the upper portions of side plates 13 and 14 are resistance heating elements 51 and 52 respectively, arranged to keep the upper portion of the device at substantially the same temperature as the lower portion. The strap 19 being coated is guided into the coating composition beneath a roller 53 and thence through a funnel shaped passageway leading to wiper heads 17 and 19 and through the slot 30. By keeping the device at an elevated temperature, the coating material is kept from setting prior to reaching the slot.

In order to facilitate the lacing of the strap through the device lever 26 is provided with operating handle 54 by means of which the lever may be swung clockwise so :as to substantially enlarge the slot 30 and the inner faces E wiper heads 17 and 19 are beveled respectively at 55 and 56. It is also generally helpful to lace the strap through the device before positioning the device within the tank. After the strap is passed through the opened :slot 30, handle 54 is released thus permitting spring 31 :to move the wiper head 19 to the adjusted position per- :mitted by the adjustment screw 35. If the coating composition is of a highly viscous nature such as a hot melt resin, a very large excess of coating is picked up by the :strap even though it does not pass deeply into the melt. As the excessively coated strap is drawn through slot 359, all except the desired thickness of coating is stripped off. This stripped oft" excess runs back into the tank between the outwardly diverging inner edges of wipers 15 and 18. From slot 30 the strap proceeds out of the tank and around a plurality of chilled rolls 57 whereby the coating material remaining on the strap is hardened or set. From chilled rolls 57 the strap proceeds to a suitable wind up mechanism. Slot 30 is preferably in alignment between the bottom of guide roll 53 and the top of the first chill roll 57 so that the wiping action of heads 17 and 19 is the same. In other words, so that the strap will bear with equal pressure against both wiping surfaces. To assure this straight line passage of the strap through slot 30 a pair of guide pins 58 and 59 may. be provided, said pins being mounted in side plates 13 and 14 and extending through the passage between said plates. However, these guide pins are not essential if the device is properly positioned so that slot 30 is on a straight line between guide roll 53 and the first chill roll 57. p

When a knot 12 in one of the strands of the strap reaches slot 30 the knot forces head 19 of wiper member 1% away from the cooperating wiper'head 17, the beveled edges 55 and 56 permitting the knot to have this result without snagging on the edges of the wiper heads.

Preferably wiper heads 17 and 19 are made separate from wiper members 15 and 18 as shown in order to permit easy replacement thereof since these are the parts receiving the greatest wear but if desired, they may obviously be an integral part of their respective wiper members.

Having thus described the invention, what is claimed is:

1. A device for removing excess hot coating from a freshly coated strap, said device comprising a pair of side plates having parallel planar inner faces spaced apart a distance slightly greater than the width of the strap, a first wiper member fixed to and between said side plates, said wiper member having a wiper head with ends abutting the inner faces of said side plates, at second Wiper member articulated between said side plates for movement toward and away from said first wiper member, said second wiper member fitting 'slidably between the inner faces of said side plates, said side plates an'd wiper members providing a substantially rectangular slot therebetween through which an excessively. coated strap may be drawn for controlled removal of excess coating, a lever pivotally mounted on the outside .of one of said side plates, means extending through the said one of said side plates and connecting said lever to the second wiper member, resilient means urging said lever in a direction to move said second wiper member toward said first wiper member, and adjustable means for limiting the movement of said second wiper member toward said first Wiper member.

2. The device set forth in claim 1 wherein said adjustable means comprises a screw associated with said lever and a screw engaging abutment on the side plate on which the lever is pivotally mounted.

3. The device set forth in claim 2 wherein said lever is provided with manually operable means for moving said lever against the action of said resilient means in order to space said wiper members relatively far apart to facilitate the lacing of the strap through the device.

References Cited by the Examiner UNITED STATES PATENTS 2,033,379 3/1936 Jenkins et a1. 118-101 2,346,697 4/1944 Mungall 118125 2,860,597 11/1958 Works et a1. 118-413 2,960,062 11/1960 Martuch 118-125 X CHARLES A. WILLMUTH, Primary Examiner.

L. G. MACHLIN, Assistant Examiner. 

1. A DEVICE FOR REMOVING EXCESS HOT COATING FROM A FRESHLY COATED STRAP, SAID DEVICE COMPRISING A PAIR OF SIDE PLATES HAVING PARALLEL PLANAR INNER FACES SPACED APART A DISTANCE SLIGHTLY GREATER THAN THE WIDTH OF THE STRAP, A FIRST WIPER MEMBER FIXED TO AND BETWEEN SAID SIDE PLATES, SAID WIPER MEMBER HAVING A WIPER HEAD WITH ENDS ABUTTING THE INNER FACES OF SAID SIDE PLATES, A SECOND WIPER MEMBER ARTICULATED BETWEEN SAID SIDE PLATES FOR MOVEMENT TOWARD AND AWAY FROM SAID FIRST WIPER MEMBER, SAID SECOND WIPER MEMBER FITTING SLIDABLY BETWEEN THE INNER FACES OF SAID SIDE PLATES, SAID SIDE PLATES AND WIPER MEMBERS PROVIDING A SUBSTANTIALLY RECTANGULAR SLOT THEREBETWEEN THROUGH WHICH AN EXCESSIVELY COATED STRAP MAY BE DRAWN FOR CONTROLLED REMOVAL OF EXCESS COATING, A LEVER PIVOTALLY MOUNTED ON THE OUTSIDE OF ONE OF SAID 